Process for the production of sugars from biomass derived from guayule plants

Abstract

A process for production of sugars from biomass derived from guayule plants includes placing a certain amount of the biomass in contact with a certain amount of water and with at least one organic acid. The sugars thus obtained may advantageously be used as sources of carbon in fermentation processes for the production of alcohols, lipids, diols, or in chemical synthesis processes for the production of other intermediates or chemicals.

What is claimed is: 
     
       1. A process for the production of sugars from biomass derived from guayule plants comprising placing an amount of said biomass G 2  in grams (g) in contact with an amount of water G 1  in g and with at least one organic acid, and optionally at least one inorganic acid, obtaining a mixture, wherein said at least one organic acid and said at least one inorganic acid optionally present being used in such amounts that the total moles of said at least one organic acid and said at least one inorganic acid optionally present m TOT  contained in said mixture are calculated according to the following equation (1):
     m   TOT   =m   1   +m   2   (1)
 
 wherein m 1  and m 2  are defined according to the following equations (2) and (3), respectively:
     m   1 =R 1   ·G   1   (2)
 
     m   2 =R 2   ·G   2   (3)
 
 
 wherein: 
 R 1  in mmol/g is the ratio of a first amount of said at least one organic acid in mmol and a first amount of said at least one inorganic acid in mmol optionally present to the amount of water G 1  in g used, R 1  being between 0.06 mmol/g and 0.25 mmol/g, said first amount of said at least one organic acid in mmol and said first amount of said at least one inorganic acid in mmol optionally present being dependent upon the amount of water G 1  in g; 
 R 2  in mmol/g is:
 in the absence of said at least one inorganic acid, the ratio between a second amount of said at least one organic acid in mmol and the amount of biomass G 2  in g used; or 
 in the presence of said at least one inorganic acid, the ratio between the sum of said second amount of said at least one organic acid in mmol and of a second amount of said at least one inorganic acid in mmol and the amount of biomass G 2  in g used; or 
 in the presence of said second amount of said at least one inorganic acid in mmol and in the absence of said second amount of said at least one organic acid in mmol, the ratio between said second amount of said at least one inorganic acid in mmol and the amount of biomass G 2  in g used; said second amount of said at least one organic acid in mmol and said second amount of said at least one inorganic acid in mmol being dependent upon the amount of biomass G 2  in g; 
 
 R 2  being between 0.90 R in mmol/g and 1.10 R in mmol/g, R being determined by means of the following algorithm (4), said algorithm (4) being obtained through the following elementary operations: 
 (i) preparing a volume V in L of an aqueous solution of said at least one organic acid that is the same or different from said first amount of said at least one organic acid and said at least a first amount of said at least one inorganic acid in mmol optionally present, said aqueous solution having a pH (1)  lower than 7; 
 (ii) adding an amount of biomass Q in g, dried at 120° C. for 15 h, to the aqueous solution obtained in (i), said amount of biomass being lower than or equal to 60% by weight with respect to the total weight of the mixture obtained; 
 (iii) measuring the pH of the mixture obtained in (ii), said pH being referred to below as pH (2) ; 
 (iv) determining R according to the following algorithm (4):
   R=(10 −pH   (1) −10 −pH   (2) )·1000· V/Q )  (4)
 
 
 wherein pH (1) , pH (2) , V and Q have the same meanings as above, the above elementary operations being carried out at room temperature; 
 provided that said at least one organic acid is present in an amount such that an R MINIMUM  ratio in mmol/g defined according to the following equation (5):
   R MINIMUM   =m   ORGANIC ACID   /G   2   (5)
 
 
 wherein m ORGANIC ACID  is a mmol of organic acid present and G 2  has the same meaning as above, R MINIMUM  is greater than or equal to 0.20 mmol/g, and, if said at least one inorganic acid is present, said mmol of organic acid in m ORGANIC ACID  is present in an amount smaller than the sum of the two amounts of acid, that is the sum of the amount of inorganic acid in mmol in equation (1) above and of the amount of organic acid in mmol in equation (1) above, said sum corresponding to the total m TOT  in mmol moles as defined in equation (1) above. 
 
     
     
       2. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein said biomass derived from guayule plants is a bagasse derived from an extraction process to which said guayule plants are subjected. 
     
     
       3. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein said biomass is subjected to a preliminary grinding process before being placed in contact with water and with said at least one organic acid and optionally at least one inorganic acid. 
     
     
       4. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein said at least one organic acid is selected from alkylsulfonic acids having general formula (I):
   R—SO 3 H  (I)
 
 wherein R represents a linear or branched C 1 -C 6  alkyl group. 
 
     
     
       5. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein said at least one inorganic acid is at least one strong inorganic acid selected from the group consisting of: hydrochloric acid (HCl), nitric acid (HNO 3 ), sulfuric acid (H 2 SO 4 ), and mixtures thereof. 
     
     
       6. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein said process comprises:
 (a) placing an amount of said biomass G 2  in g in contact with an amount of water G 1  in g and with at least one organic acid and optionally at least one inorganic acid, in a reactor, obtaining a first reaction mixture; 
 (b) heating the reactor to the desired temperature between 100° C. and 180° C., in a time of between 20 minutes and 2 hours, obtaining a second reaction mixture comprising a first solid phase and a first aqueous phase; 
 (c) optionally, holding said second reaction mixture comprising a first solid phase and a first aqueous phase at said desired temperature for a time of between 30 seconds and 1 hour; 
 (d) recovering said second reaction mixture from said reactor. 
 
     
     
       7. The process for the production of sugars from biomass derived from guayule plants according to  claim 6 , wherein:
 said biomass is present in said first reaction mixture in in amounts of between 1% by weight and 60% by weight, with respect to the total weight of said first reaction mixture; and/or 
 said reactor is selected from slurry reactors with continuous biomass feed; and/or 
 said first solid phase comprises lignin and cellulose and said first aqueous phase comprises at least one sugar having 5 carbon atoms or at least one sugar having 5 carbon atoms and at least one sugar having 6 carbon atoms, and said at least one organic acid and optionally said at least one inorganic acid. 
 
     
     
       8. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein said guayule plants are of the species  Parthenium argentatum.    
     
     
       9. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein R1 is between 0.09 mmol/g and 0.18 mmol/g. 
     
     
       10. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein the pH (1)  is between 0.7 and 3. 
     
     
       11. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein R2 is between 0.95 R in mmol/g and 1.05 R in mmol/g. 
     
     
       12. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein said amount of biomass Q is between 2% by weight and 40% by weight. 
     
     
       13. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein R MINIMUM  is greater than or equal to 0.25 mmol/g. 
     
     
       14. The process for the production of sugars from biomass derived from guayule plants according to  claim 3 , wherein said biomass is ground to obtain particles having a diameter of between 0.5 mm and 4 mm. 
     
     
       15. The process for the production of sugars from biomass derived from guayule plants according to  claim 3 , wherein said biomass is ground to obtain particles having a diameter of lower than 2 mm. 
     
     
       16. The process for the production of sugars from biomass derived from guayule plants according to  claim 3 , wherein said biomass is ground to obtain particles having a diameter of between 0.1 mm and 10 mm. 
     
     
       17. The process for the production of sugars from biomass derived from guayule plants according to  claim 4 , wherein R represents a linear or branched C 1 -C 3 , alkyl group. 
     
     
       18. The process for the production of sugars from biomass derived from guayule plants according to  claim 4 , wherein R represents methanesulfonic acid (CH 3 —SO 3 H). 
     
     
       19. The process for the production of sugars from biomass derived from guayule plants according to  claim 5 , wherein the strong inorganic acid is sulfuric acid (H 2 SO 4 ). 
     
     
       20. The process for the production of sugars from biomass derived from guayule plants according to  claim 1 , wherein said process comprises:
 (a) placing an amount of said biomass G 2  in g in contact with an amount of water G 1  in g and with at least one organic acid and at least one inorganic acid, in a reactor, thereby obtaining a first reaction mixture; 
 (b) heating the reactor to the desired temperature between 100° C. and 180° C., in a time of between 20 minutes and 2 hours, thereby obtaining a second reaction mixture comprising a first solid phase and a first aqueous phase; 
 (d) optionally, holding said second reaction mixture comprising a first solid phase and a first aqueous phase at said desired temperature for a time of between 30 seconds and 1 hour; and 
 (e) recovering said second reaction mixture from said reactor.